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Cogsci/Psychology 127: Lecture 9 Object Recognition

Cogsci/Psychology 127: Lecture 9 Object Recognition. First Exam: Monday, October 6 FORMAT: Multiple Choice, Short Answer, Essay Essay: Describe experiment w/ graph! Bring small SCANTRON No scheduled make-ups. Notify me (not GSI) early if there is a problem. Review:

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Cogsci/Psychology 127: Lecture 9 Object Recognition

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  1. Cogsci/Psychology 127: Lecture 9 Object Recognition

  2. First Exam: Monday, October 6 FORMAT: Multiple Choice, Short Answer, Essay Essay: Describe experiment w/ graph! Bring small SCANTRON No scheduled make-ups. Notify me (not GSI) early if there is a problem. Review: Last year’s exams are posted. Good study guide. Textbook, Reader guide. Question and Answer Session: Wednesday, October 1, 5:30 pm. Tolman 5101

  3. akinetopsia achromatopsia

  4. Specializations in visual areas to support different types of computations. Where are these things: Spatial perception Dorsal pathway What is in the environment: Object recognition Ventral pathway

  5. Specializations in visual areas to support different types of computations. Where are these things: Spatial perception Dorsal pathway Recognition for Action What is in the environment: Object recognition Ventral pathway

  6. Double Dissociation in Support of Two-Stream Hypothesis Optic ataxia Impairments of visually guided reaching despite normal object recognition. Difficulty using vision for action. Lesions of parietal lobe:

  7. Double Dissociation in Support of Two-Stream Hypothesis Optic ataxia Impairments of visually guided reaching despite normal object recognition. Difficulty using vision for action. Lesions of parietal lobe: Spared reaching despite severe object recognition problems. Much more counter-intuitive. Patient DF

  8. Double Dissociation in Support of Two-Stream Hypothesis Optic ataxia Impairments of visually guided reaching despite normal object recognition. Difficulty using vision for action. Lesions of parietal lobe: Spared reaching despite severe object recognition problems. Implications for consciousness: Vision for action system can operate outside awareness.

  9. Top: Lesion reconstruction in DF in 2003 (hypoxia in 1988) Bottom: Region activated in fMRI in normal individuals during object recognition task (Objects – Scrambled Shapes)

  10. Seeing without a ventral stream Case report of 30-year old man who had bilateral meningoencephalitis at age 3. Bilateral ventral stream lesions. Dorsal lesion only on right side. Thus, “sees” with only left dorsal stream.

  11. Seeing without a ventral stream 30-year old man who had bilateral meningoencephalitis at age 3 affecting ventral stream bilaterally. Impairments: Severe “what” deficit (functionally blind) Achromatopsia Unable to read, recognize people or objects, discern simple texture boundaries. Educated at school for visually impaired.

  12. Seeing without a ventral stream 30-year old man who had bilateral meningoencephalitis at age 3 affecting ventral stream bilaterally. Impairments: Severe “what” deficit (functionally blind) Achromatopsia Unable to read, recognize people or objects, discern simple texture boundaries. Educated at school for visually impaired. Spared: Able to use visual information for action (“how”) Could walk unaided, play ping pong, juggle. Even drove a motorcycle (though classified as “blind”)

  13. Deficits of Object Recognition: Video segments 1.1 to 1.3 (start, 0:00 to 5:48)

  14. Visual Agnosia from gnostic, knowledge Deficit in recognizing a visually presented object that can not be attributed to basic sensory abilities.

  15. Visual Agnosia from gnostic, knowledge Deficit in recognizing a visually presented object that can not be attributed to basic sensory abilities. Modality specific: Subtypes: visual, auditory Object recognition deficit that is more general is considered a memory disorder.

  16. Errors are usually visually related “Fencer’s Mask” “Rose twig”

  17. Problems in identifying coherent parts of the visual scene. Patient CK was unable to name the three shapes yet accurate reproduction.

  18. Visual memory can be intact: Drawings from memory by Patient CK

  19. Visual knowledge may fade over time 1985: 4 years post-stroke 1995: 14 years post-stroke Celery Owl

  20. Subtypes of Visual Agnosia Apperceptive agnosia Failure to organize a coherent percept. What is it?

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